The Army is to lose 17 major units in the biggest overhaul of the service for decades, it has been announced.

Defence Secretary Philip Hammond said the changes were needed to create a "balanced, capable and adaptable force" for the future.

Among the units to go are four infantry battalions - the 2nd Battalion the Royal Regiment of Fusiliers, the 2nd Battalion the Yorkshire Regiment (Green Howards), the 3rd Battalion the Mercian Regiment, and the 2nd Battalion the Royal Welsh.

A fifth, the 5th Battalion the Royal Regiment of Scotland (Argyll and Sutherland Highlanders) will be reduced to a public duties company to carry out public duties in Scotland.

The Armoured Corps will be reduced by two units with the merger of the Queen's Royal Lancers and the 9th/12th Royal Lancers and the 1st and 2nd Tank Regiments amalgamating.

There will also be reductions in the number of units in the Royal Artillery, the Royal Engineers, the Army Air Corps, the Royal Logistic Corps, the Royal Electrical and Mechanical Engineers and the Royal Military Police.

The changes - to be completed by the end of the decade - will see the regular Army cut from 102,000 to 82,000 while the Territorial Army will be expanded to give a combined force of 120,000.

"After inheriting a massive overspend from the last Government, we have had to make tough decisions to implement our vision of a formidable, adaptable and flexible armed forces," Mr Hammond said.

"After a decade of enduring operations, we need to transform the Army and build a balanced, capable and adaptable force ready to face the future. Army 2020 will create a more flexible and agile Army. Unlike the past, it will be set on a firm foundation of men and material, well trained, well equipped and fully funded. The regimental system will remain the bedrock of the Army's fighting future."

Shadow defence secretary Jim Murphy accused ministers of putting "savings before strategy". He said: "Jobs and military capability have been lost and tradition and history have been sacrificed. This isn't just a smaller Army, it's also a less powerful Army in a less influential nation. Our armed forces and their families deserve better."